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author | Johannes Berg <johannes.berg@intel.com> | 2015-01-16 22:09:00 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-01-18 01:03:45 -0500 |
commit | 053c095a82cf773075e83d7233b5cc19a1f73ece (patch) | |
tree | c787028efa9a73a182a0f338f87b6294cef4b8b9 /net/netfilter | |
parent | ede58ef28e105de94475b2b69fa069c9a2ce6933 (diff) | |
download | linux-stable-053c095a82cf773075e83d7233b5cc19a1f73ece.tar.gz linux-stable-053c095a82cf773075e83d7233b5cc19a1f73ece.tar.bz2 linux-stable-053c095a82cf773075e83d7233b5cc19a1f73ece.zip |
netlink: make nlmsg_end() and genlmsg_end() void
Contrary to common expectations for an "int" return, these functions
return only a positive value -- if used correctly they cannot even
return 0 because the message header will necessarily be in the skb.
This makes the very common pattern of
if (genlmsg_end(...) < 0) { ... }
be a whole bunch of dead code. Many places also simply do
return nlmsg_end(...);
and the caller is expected to deal with it.
This also commonly (at least for me) causes errors, because it is very
common to write
if (my_function(...))
/* error condition */
and if my_function() does "return nlmsg_end()" this is of course wrong.
Additionally, there's not a single place in the kernel that actually
needs the message length returned, and if anyone needs it later then
it'll be very easy to just use skb->len there.
Remove this, and make the functions void. This removes a bunch of dead
code as described above. The patch adds lines because I did
- return nlmsg_end(...);
+ nlmsg_end(...);
+ return 0;
I could have preserved all the function's return values by returning
skb->len, but instead I've audited all the places calling the affected
functions and found that none cared. A few places actually compared
the return value with <= 0 in dump functionality, but that could just
be changed to < 0 with no change in behaviour, so I opted for the more
efficient version.
One instance of the error I've made numerous times now is also present
in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't
check for <0 or <=0 and thus broke out of the loop every single time.
I've preserved this since it will (I think) have caused the messages to
userspace to be formatted differently with just a single message for
every SKB returned to userspace. It's possible that this isn't needed
for the tools that actually use this, but I don't even know what they
are so couldn't test that changing this behaviour would be acceptable.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netfilter')
-rw-r--r-- | net/netfilter/ipvs/ip_vs_ctl.c | 9 | ||||
-rw-r--r-- | net/netfilter/nf_tables_api.c | 18 |
2 files changed, 18 insertions, 9 deletions
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index b8295a430a56..e55759056361 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -2887,7 +2887,8 @@ static int ip_vs_genl_dump_service(struct sk_buff *skb, if (ip_vs_genl_fill_service(skb, svc) < 0) goto nla_put_failure; - return genlmsg_end(skb, hdr); + genlmsg_end(skb, hdr); + return 0; nla_put_failure: genlmsg_cancel(skb, hdr); @@ -3079,7 +3080,8 @@ static int ip_vs_genl_dump_dest(struct sk_buff *skb, struct ip_vs_dest *dest, if (ip_vs_genl_fill_dest(skb, dest) < 0) goto nla_put_failure; - return genlmsg_end(skb, hdr); + genlmsg_end(skb, hdr); + return 0; nla_put_failure: genlmsg_cancel(skb, hdr); @@ -3215,7 +3217,8 @@ static int ip_vs_genl_dump_daemon(struct sk_buff *skb, __u32 state, if (ip_vs_genl_fill_daemon(skb, state, mcast_ifn, syncid)) goto nla_put_failure; - return genlmsg_end(skb, hdr); + genlmsg_end(skb, hdr); + return 0; nla_put_failure: genlmsg_cancel(skb, hdr); diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 3b3ddb4fb9ee..70f697827b9b 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -427,7 +427,8 @@ static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net, nla_put_be32(skb, NFTA_TABLE_USE, htonl(table->use))) goto nla_put_failure; - return nlmsg_end(skb, nlh); + nlmsg_end(skb, nlh); + return 0; nla_put_failure: nlmsg_trim(skb, nlh); @@ -971,7 +972,8 @@ static int nf_tables_fill_chain_info(struct sk_buff *skb, struct net *net, if (nla_put_be32(skb, NFTA_CHAIN_USE, htonl(chain->use))) goto nla_put_failure; - return nlmsg_end(skb, nlh); + nlmsg_end(skb, nlh); + return 0; nla_put_failure: nlmsg_trim(skb, nlh); @@ -1707,7 +1709,8 @@ static int nf_tables_fill_rule_info(struct sk_buff *skb, struct net *net, nla_put(skb, NFTA_RULE_USERDATA, rule->ulen, nft_userdata(rule))) goto nla_put_failure; - return nlmsg_end(skb, nlh); + nlmsg_end(skb, nlh); + return 0; nla_put_failure: nlmsg_trim(skb, nlh); @@ -2361,7 +2364,8 @@ static int nf_tables_fill_set(struct sk_buff *skb, const struct nft_ctx *ctx, goto nla_put_failure; nla_nest_end(skb, desc); - return nlmsg_end(skb, nlh); + nlmsg_end(skb, nlh); + return 0; nla_put_failure: nlmsg_trim(skb, nlh); @@ -3035,7 +3039,8 @@ static int nf_tables_fill_setelem_info(struct sk_buff *skb, nla_nest_end(skb, nest); - return nlmsg_end(skb, nlh); + nlmsg_end(skb, nlh); + return 0; nla_put_failure: nlmsg_trim(skb, nlh); @@ -3324,7 +3329,8 @@ static int nf_tables_fill_gen_info(struct sk_buff *skb, struct net *net, if (nla_put_be32(skb, NFTA_GEN_ID, htonl(net->nft.base_seq))) goto nla_put_failure; - return nlmsg_end(skb, nlh); + nlmsg_end(skb, nlh); + return 0; nla_put_failure: nlmsg_trim(skb, nlh); |